CORROSION REMOVAL

Abstract: An apparatus for shot balsting corrosion from roadside barriers (1). Abrasive is projected onto the barrier (1) from a head assembly supported on a vehicle. The head assembly is moved relative to the vehicle to maintain a predetermined position relative to the barrier, and defines a chamber with the barrier (1) within which the abrasive is projected. Projected abrasive is collected from the head assembly and sucked back to the vehicle, cleaned to remove debris dislodged from the barrier (1), and returned to a vehicle-mounted hopper for re-use in the head assembly. The abrasive is projected from an array of nozzles (7, 8, 9, 10).

Description: CORROSION REMOVAL The present invention relates to an apparatus for removing corrosion from an elongate structure of uniform shape, for example a crash barrier extending along the side of a roadway. Crash barriers are provided alongside many roads, and in particular major roads. The crash barriers are usually in the form of lengths of steel which extend alongside the edge of the road and are supported on upright posts. Crash barriers are an effective way of preventing vehicles leaving a road and there are many thousands of miles of crash barriers installed around the world. In order to improve the visibility of crash barriers, and to protect them from physical deterioration in the hostile environments in which they are installed, it is desirable to periodically paint the crash barriers. It is highly desirable, however, to clean the crash barriers before they are painted to remove dirt and rust. If the crash barriers are not cleaned before painting the paint does not stick effectively on the barrier and as a result the appearance of recently painted crash barriers is not acceptable and the objective of protecting the crash barriers against corrosion is not met. It would of course be possible to thoroughly clean the crash barriers before repainting, for example using conventional sand blasting or shot blasting equipment, but this has proved to be an unacceptable approach to adopt. Firstly, the process takes a great deal of time, resulting in high costs and an unacceptable disruption to use of the road adjacent to which the barrier being cleaned is located. Secondly, it is not possible to prevent abrasives used in blasting procedures from being lost into the environment adjacent the barrier being cleaned. It is an object of the present invention to provide an apparatus to obviate or mitigate the problems outlined above. According to the present invention, there is provided an apparatus for removing corrosion from an elongate structure of uniform shape, comprising a head assembly which is movably supported on a vehicle, means for moving the head relative to the vehicle to maintain the head in a predetermined position relative to a structure alongside which the supporting vehicle is driven, and means for projecting abrasive from the head onto the surface of the structure, the head being dimensioned to define with the structure a chamber within which the abrasive is projected. The head may comprise resilient upper, lower and side members, the side members being shaped in vertical section to conform to a vertical section through the structure, and the upper and lower members defining lips which engage behind upper and lower edges of the structure. A number of abrasive projecting nozzles may be located within the head assembly. The nozzles may be fixed in position relative to the head or may be oscillated in the vertical direction to ensure full coverage of the surface to be cleaned. Projected abrasive may be collected by, for example, a vacuum system, returned to the vehicle, cleaned and re-circulated for re-use. An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a schematic illustration of the head assembly of an embodiment of the present invention looking in the direction of travel of a vehicle supporting that head assembly; Fig. 2 is a side view of a full vehicle-mounted system in accordance with the present invention; Fig. 3 is a top view of the vehicle illustrated in Fig. 2; and Fig. 4 is a schematic view of a modified head assembly of the present invention, looking in the direction of travel of a vehicle supporting that head assembly. Referring to Fig. 1, this is a sectional view through the head assembly of an apparatus in accordance with the present invention looking in the direction of travel of that head assembly along a crash barrier 1 which is mounted on vertically extending posts (not shown). The head assembly comprises a rear wall 2, an upper wall 3, a lower wall 4, lips 5 extending from the upper and lower walls, and two side walls 6. The various components of the head assembly define with the barrier 1 a cavity into which abrasive is projected from four nozzles 7, 8, 9 and 10. The nozzles are pivotally mounted so as to pivot about horizontal axes extending through the points indicated by dots 11 in Fig. 1. This enables the abrasive sprayed from the nozzles, represented schematically by lines 12, to provide full coverage over the left-hand surface of the barrier 1. An outlet 13 is provided at the bottom of the head assembly and an air inlet 14 is provided at the top of the head assembly. Abrasive projected onto the barrier 1 falls towards the bottom of the head assembly and is entrained by the air supplied through inlet 14. Suction equipment then draws the abrasive and any material dislodged from the barrier 1 through the outlet 13. Referring now to Figs. 2 and 3, these show schematic views of the vehicle-mounted apparatus which incorporates the head assembly illustrated in Fig. 1. The vehicle includes a large lorry which is adapted to carry shot blasting apparatus and an arm to support the head assembly of Fig. 1 in an appropriate orientation relative to a crash barrier to be cleaned. The head assembly of Fig. 1 is identified in Figs. 2 and 3 by reference numeral 15. The assembly 15 is mounted at the end of an arm assembly 16 which can be extended in a horizontal direction and can be moved in the vertical direction by an assembly 17. Wheels 18 are intended to contact the central portion of a conventional road barrier which defines a track along which the wheels are in effect guided. In dependence upon the forces applied to the wheels 18, the arm 16 is extended and retracted pneumatically, and/or hydraulically and the elevating assembly 17 is extended and retracted pneumatically and/or hydraulically. Thus the position of the head 15 is maintained substantially constant relative to the crash barrier to be cleaned, the head being moved along the length of the barrier as the result of the forward movement of the vehicle. In use, the vehicle travels along the length of the barrier to be cleaned, applying shot blast material which is referred to below as grit from a hopper 19 through the head assembly 15. The grit is projected at high velocity onto the surface of the barrier to effect a thorough cleaning action. Used grit and debris from the surface of the barrier are drawn from the bottom of the head 15 and this collected material is drawn under suction through a separator 20. Within the separator 20 re-usable grit is separated from spent grit and debris and is then returned to the hopper 19. Debris and spent grit are collected in filters 21 located beneath a vacuum system 22. The collected debris and dust can be disposed of in a controlled manner subsequently. Thus it will be apparent that the described vehicle is not only capable of effectively cleaning crash barriers in an efficient and rapid manner but it is also capable of minimising the wastage of shot blasting material. This has the advantage not only of reducing the amount of shot blasting material that must be supplied but also in reducing pollution in the environment immediately around the barrier being cleaned. The power source for the cleaning operation as well as the various movements of the head support arms, etc. comes from a compressor 23. This is an ultra high volume high pressure machine. In the illustrated case the compressor is mounted on a separate trailer 24. The pressurised air from the compressor is dried in an air cooler 25 and an air receiver 26. These devices have the effect of removing moisture from the air, thereby preventing blockages in the shot blasting system as well as ensuring that the final blast is below an acceptable humidity level. This prevents premature corrosion of a cleaned barrier surface. From the air receiver 26 the air goes to the blasting head. As described with reference to Fig. 1, the blasting head comprises four nozzles 7, 8, 9 and 10. As shown in Fig. 2, these nozzles are arranged in two adjacent holders, nozzles 7 and 9 being arranged in one holder and nozzles 8 and 10 in the other. Each of these nozzles is connected to a blasting pot 27 which contains a measure of grit that is held under pressure. The grit is then fed into the flow of compressed air via control valves located at the bottom of each pot. The mixture of grit and high pressure air travels down pipes 28 to the blasting head 15. As described with reference to Fig. 1, the nozzles 7 to 10 are oscillated in the vertical direction to achieve full coverage of the barrier to be cleaned. The number of oscillations per second is controlled by the pneumatic assembly in the illustrated case although other methods of achieving the desired oscillation are possible, for example cams or similar cyclical motion devices. The rate of the oscillation is preferably directly proportional to the forward speed of the vehicle to ensure an appropriate coverage of the barrier to be cleaned. This proportionality can be achieved by direct transfer of vehicle motion from a standard engine, gear box, differential assembly used to move from one site to another to a hydraulic drive. To allow total and controllable variation in speed a hydraulic drive system 29 is provided to power the standard drive shaft when the gear box is in neutral. This hydraulic drive can be controlled by the vehicle driver to cover exact speeds from 0 to 10 kph, and this in turn can be linked via microprocessor to set the optimum number of oscillations at the head. The resilient rubber cover illustrated in Fig. 1 which shrouds the head 15 to thereby contain the ricocheting grit and return it to the vehicle is of course linked to the vacuum unit 22. The vacuum unit 22 is rated at a higher specification than the compressor 23 to create a "negative pressure" to thereby prevent dust escaping. The vacuum system draws everything into the separator where the re¬ usable grit is extracted for re-use. The effective separation required is achieved by drawing everything across the width of the main hopper 19, allowing heavier, re-usable particles to fall to the bottom while the lighter "waste" is drawn out of an outlet 30. This waste is then filtered from the carrier air in the large surface area filters 21. Control of all the system variables is made via a control panel 31 which enables control of: compressed air supply on/off blasting pots on/off regulating grit supply from pots speed of vehicle frequency of oscillation of nozzles manual override of arm assembly vacuum regulation, volume and pressure re-loading valves The described vehicle may be used in applications other than those involving shot blasting roadway crash barriers. It is quite possible that a vehicle could be simply modified to enable operations to be carried out on similar elongate structures, for example white lines on roads, and both vertical and horizontal surfaces of buildings. It will be appreciated that the detailed structure of the head assembly may be modified considerably from that described above. For instance, the head may be provided with more or less than 4 nozzles and the nozzles may be fixed in position, oscillating, or a combination of fixed and oscillating nozzles. Similarly, the orientation of nozzles within the head assembly may be modified, as may the grouping and mounting of the nozzles. In addition, modifications may be made to the overall configuration of the head, e.g. the shape of the walls 3, 4 and 6, for instance, to accommodate different numbers and arrangements of nozzles. One example of an alternative head assembly in accordance with the present invention is illustrated in Figure 4, in which the same reference numerals as used above are used to designate corresponding features. Referring to the drawings front portions of the upper wall 3 and lower wall 4 of the head assembly are angled inwards, terminating in lips 5. The side walls 6 are shaped to correspond with the configuration of the upper and lower walls 3 and 4. Six nozzles 28 are housed within the cavity formed between the head assembly walls 3, 4 and 6. The nozzles 28 are fixed to a support frame 29 by pins 30. The six nozzles may be positioned as shown, or re-arranged in any of the thirteen alternative nozzle positions shown in broken lines. The shape of the support frame 29 is such that the nozzles are arranged in three mutually inclined orientations, that is a central group of three nozzles in region 31 directed generally horizontally towards the barrier 1, an upper group of two nozzles in region 32, and a lower nozzle in region 33. The upper and lower nozzles are angled inwards towards the upper and lower positions of the crash barrier 1. Although the nozzles 28 do not oscillate, adequate coverage of all the surface of a range of barrier configurations may be achieved by appropriate location of the six nozzles in the nineteen available nozzle support positions. In practice, good results have been achieved using only four fixed nozzles, two directed horizontally, one at an angle downwards and one at an angle upwards. An air outlet 13 is provided at the bottom of the head assembly, and an air inlet 14 is provided at the top of the head assembly, for entraining and removing particles from the head in the manner described above. It will be appreciated that other features of the apparatus may be modified to complement modifications made to the head assembly. For instance to accommodate an increase in the number of nozzles used in the head shown in Figure 4, additional blasting pots 27 may be incorporated in the apparatus. Alternatively, fewer, but larger blasting pots may be used, e.g. two 5 ton high pressure blast pots may be used. It will be understood that additional alterations or modifications may be made to the head assembly or to any other features of the apparatus without one parting from the present invention.

Claims: CLAIMS 1. An apparatus for removing corrosion from an elongate structure of uniform shape, comprising a head assembly which is movably supported on a vehicle, means for moving the head relative to the vehicle to maintain the head in a predetermined position relative to a structure alongside which the supporting vehicle is driven, and means for projecting abrasive from the head onto the surface of the structure, the head being dimensioned to define with the structure a chamber within which the abrasive is projected. 2. An apparatus according to claim 1, wherein the head comprises resilient upper, lower and side members, the side members being shaped in vertical section to conform to a vertical section through the structure, and the upper and lower members defining lips which engage behind upper and lower edges of the structure. 3. An apparatus according to claim 1 or 2, comprising a plurality of abrasive projecting nozzles located within the head assembly. 4. An apparatus according to claim 3, wherein the nozzles are mounted in a support frame defining alternative nozzle support positions such that the nozzle positions may be selectively modified. 5. An apparatus according to any preceding claim, comprising means for vertically oscillating the direction of projection of the abrasive projecting means. 6. An apparatus according to any preceding claim, comprising means for collecting projected abrasive and returning the collected abrasive to a storage device or the vehicle. 7. An apparatus according to claim 5, wherein the collecting means comprises a suction device for sucking abrasive from the head. 8. An apparatus according to claim 5 or 6, comprising means for separating abrasive from debris dislodged from the barrier. 9. An apparatus substantially as hereinbefore described with reference to the accompanying drawings.

Inventors: LEE GARY FRANCIS, LEE, GARY, FRANCIS
Applicants: HIGHWAY SAFETY SYSTEMS LTD, LEE GARY FRANCIS, HIGHWAY SAFETY SYSTEMS LIMITED, LEE, GARY, FRANCIS
Application year: 1994
Main classification: B24C3
IPC codes: B24C3, E01H1